A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power an aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine may include, for example, a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is positioned at the front of the engine, and includes a fan that induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The remaining fraction of induced air is accelerated into and through a bypass plenum, and out the exhaust section.
The compressor section is configured to raise the pressure of the air to a relatively high level. In particular, the compressor section includes an impeller that has a plurality of vanes extending therefrom that accelerate and compress the air. The compressed air then exits the compressor section, and is energized by the combustor section and flowed into the turbine section to cause rotationally mounted turbine vanes to rotate and generate energy.
Over time, certain components of the engine may become worn and may need to be replaced or repaired. For example, one or more of the impeller vanes may become deformed or damaged due to prolonged exposure to high temperature air and continuous bombardment by particles during engine operation. One impeller vane repair process involves laser welding using a conventional multi-axis welding apparatus. In this regard, a laser source provides a laser beam through optics that are mounted to a multi-axially movable arm. The optics direct the laser beam through a focusing head on the arm toward a platform configured to hold the impeller. The platform moves multi-axially relative to the arm so that the laser beam can be directed at, and therefore heat and melt filler material onto, any desired area of the impeller. A gas source provides an inert gas around the laser beam and at the impeller through a conduit that extends at least partially through the focusing head. After the impeller and filler material cools and hardens, the filled area is machined into a desired configuration.
Although conventional multi-axis welding apparatus are useful, they have certain drawbacks. For example, it has been found that particles from the surrounding environment may be attracted to the apparatus and may undesirably deposit onto the optics of the apparatus. Consequently, the particles may melt onto the optics when the laser beam is directed therethrough and may contaminate and damage the apparatus. Additionally, in some cases, the inert gas may not be adequately directed to the laser beam and impeller, which may lead to inadvertent oxidation of the filler material. Moreover, because the focusing head is generally a rigid component, the head could, during welding, unintentionally contact and damage molten portions of the impeller.
Hence, there is a need for an automated welding apparatus that is capable of preventing particles from depositing onto the optics thereof. Moreover, there is a need for an apparatus that adequately directs inert gas around the laser beam and at the impeller. Additionally, it is desirable for the apparatus to include a component that prevents the focus head from directly contacting the impeller.